Display screen or portion thereof with a graphical user interface



FIG. 1 is a front view of a display screen or portion thereof with agraphical user interface, showing my new design, according to a firstembodiment thereof.

FIG. 2 is a front view of a display screen or portion thereof with agraphical user interface, showing my new design, according to a secondembodiment thereof.

FIG. 3 is a front view of a display screen or portion thereof with agraphical user interface, showing my new design, according to a thirdembodiment thereof.

FIG. 4 is a front view of a display screen or portion thereof with agraphical user interface, showing my new design, according to a fourthembodiment thereof; and,

FIG. 5 is a front view of a display screen or portion thereof with agraphical user interface, showing my new design, according to a fifthembodiment thereof.

The broken lines illustrate unclaimed portions of the display screen andform no part of the claimed design.

CLAIM The ornamental design for a display screen or portion thereof witha graphical user interface, as shown and described.